The present invention relates to image encoding and decoding apparatus and method and recording media, and in particular, to image encoding and decoding apparatus and method, and an image recording medium for obtaining a decoded image of relatively good quality while preventing an increase in the amount of data.
It is well known that images have a large amount of data. Accordingly, in general, the images are encoded (compressed) before being transmitted or recorded. When the encoding (color compression) of an image having a plurality of color components (a red-green-blue (RGB) 4:4:4 image, for example) is performed, there may be a case where one pixel (24 bits) is vector-quantized to form 8 bits where each of the R, G and B components has 8 bits. In this case, at a decoding section, a decoded image having only up to 256 (28=28) colors is obtained. This is because the average number of bits assigned to one color component is 8/3 bits. Accordingly, by increasing the number of bits assigned to one color component, deterioration in the quality of the decoded image can be suppressed. However, the amount of data also, increases in correspondence with the increase in the number of bits.
The present invention has been made in view of the foregoing circumstance, and provides a decoded image with high quality without the increase in the amount of data.
In a method for encoding image data including a plurality of pixels wherein each pixel comprises N color components, one color component is eliminated in the N color components to select Nxe2x88x921 color components. The selected Nxe2x88x921 color components are then encoded.
According to one aspect of the present invention, each of the N color components is eliminated periodically.
In a method for producing a decoded image from encoded data generated by encoding image picture that includes a plurality of pixels wherein each pixel comprises N color components and the encoded data is generated by encoding Nxe2x88x921 color components selected by eliminating one color component from the N color components, the encoded data is decoded to generate the Nxe2x88x921 color components for each pixel. The eliminated one color component is generated based on the generated Nxe2x88x921 color components that are adjacent the eliminated one color component. A pixel is produced based on the generated Nxe2x88x921 color components and the eliminated one color component that has been generated.